Fix typos [ci skip]
Merge pull request #520 from d10/docs

Fix doc typos. [ci skip]
More doc tweaks. [ci skip]
Use `ok` when appropriate in test/test.js.
Avoid var conflicts in the `support` IIFE in minified builds.
Remove unneeded `@type` tag from the underscore build. [ci skip]
Add `toJSON` alias of `valueOf`. [closes #521]
Rebuild dist.
Test format cleanup.
Add `JSON.stringify` test.
Add more `_.callback` tests.
Minor comment nit. [ci skip]
Add `null` and `undefined` values tests for `thisArg`.
Add more falsey value tests.
Ensure `_.contains` works with a `fromIndex` for objects.
Add doc note to `_.isEqual` about not supporting comparing DOM nodes or functions. [ci skip]
Ensure functions created by `_.matches` don't error when comparing falsey `object` values. [closes #523]
Add `partitionInitializer` helper.
Add `arrayEach`, `arrayEachRight` and `arrayMap` helpers.
Doc nit for `_.pairs`. [ci skip]